The present invention relates to a device for the presentation of information, characterized in that it is at the same time transparent, i.e., it enables vision of the scene at the rear of the device, and emissive, i.e., it presents the user with information in the form of light emitted by the device itself.
A device of this type is of particular interest for the vehicle sector in so far as it enables presentation of the information on two different planes, namely, the background, i.e., the external scene visible to the user through the windows of the vehicle, such as the windscreen, rear window and side windows, and the light image generated by the device.
The interest of this type of devices is not limited, however, to the vehicle sector; the advertising sector or that of information to the public are just two examples of the possible fields of application of the device.
Transparent devices based upon light-emitting diodes (LEDs) are already present in the known art; for example, the patent application No. EP1460609 describes a solution for transparent and programmable LED displays comprising: an array of LEDs in a row-column configuration, each row of said LEDs being connected by an electric wire, each column being connected to a transparent-conductive-oxide (TCO) layer deposited on the underlayer, said transparent layer being electrically insulated from said row of wires; and means for electrical turning-on associated to said array.
The use of metal wires for interconnecting the LEDs of each row enables a reduction in the voltage drops due to the electrical resistance of the row and hence use of decidedly lower supply voltages. Said metal wires are bonded on the underlayer of TCO only in areas corresponding to purposely provided pads obtained by cutting the layer of TCO along a closed circular path, so as to insulate said pads electrically from the corresponding column of TCO.
The solution described in the patent application No. EP1460609 presents a series of limitations:                the transparency is limited on account of the dimensions of the LED components in SMD format, which becomes particularly critical if the aim is to increase the density of the LEDs or reduce the dimensions of the device;        the process steps regarding the positioning of the wires constituting the rows and the corresponding operations of bonding on the pads are not obtainable using standard technologies and machinery for SMD technology, thus rendering fabrication of the device more costly;        if the dimensions of the device are reduced, the technological steps described above become more complex and the production yields decrease; and        the formation of insulated pads along the columns of TCO produces a local narrowing of the paths and hence an increase in the in-series resistance and thus limits the number of addressable rows.        